Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
  • F02D41/402—Multiple injections
  • F02D41/405—Multiple injections with post injections
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1493—Details
  • F02D41/1495—Detection of abnormalities in the air/fuel ratio feedback system
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/40—Engine management systems

Definitions

• the invention relates to a method for assessing an operation of an injection valve upon application of a drive voltage. Furthermore, the invention relates to an evaluation device for assessing an operation of an injection valve upon application of a drive voltage.
• DE 10 2006 013 166 describes a method and a control device for determining an opening tension of an injector with a piezoactuator.
• the opening of the injector is determined by the energization interrupted at a holding voltage and then measured a voltage applied to the piezoelectric actuator voltage change and compared with a comparison voltage increase.
• an injection valve for example a common-rail injector (CRI)
• the at least one actuator may be, for example, a piezoelectric actuator.
• a drive voltage is applied to the at least one actuator in this case.
• the at least one actuator then experiences an expansion due to the applied drive voltage and at the same time exerts a pressure on a switching chain arranged on the at least one actuator, which has, for example, a hydraulic coupler.
• a switching valve arranged behind the switching chain possibly a hydraulic servo valve, is moved in this way into an open position. If the switching valve is in its open position, the fuel from the fuel tank can flow into the internal combustion engine.
• the activation voltage should be selected such that the switching valve is displaced into its open position with a defined excess of force.
• the drive voltage for moving the switching valve in its open position is dependent on a rail pressure. Frequently, the drive voltage is determined individually for injector production for each injector. A characteristic curve of the control voltage determined for opening the injection valve as a function of the respective rail pressure is subsequently stored in an injection control device for controlling the injection valve. This is also called an injector-specific voltage balance (ISA).
• ISA injector-specific voltage balance
• both the at least one actuator and the switching chain are subject to drift during their lifetime. This results in a deviation in the required for opening the injector drive voltage from the original characteristic during operation of the injector in a vehicle.
• the invention provides a method with the features of claim 1 and an evaluation device with the features of claim 10.
• the inventive method is based on the finding that the number and the volume of the noise generated during a judgment of the operation of the injector upon application of a drive voltage are significantly reduced when the respective drive voltage for a non-torque-forming injection to the at least one actuator of the Injection valve is applied.
• a non-torque-forming injection is often also referred to as post-injection.
• the method according to the invention hardly any noise is formed in the case of a non-torque-forming injection.
• the driving behavior of the vehicle when carrying out the method according to the invention during a journey is hardly influenced.
• the method according to the invention can thus be carried out regularly during a journey without this being associated with a loss of comfort for the driver.
• the method according to the invention is based on the knowledge that a non-torque-forming injection which has conventionally already been installed on the vehicle for detecting a fuel content in the exhaust gas tract can be detected.
• the measured fuel content may be a fuel / air ratio or a fuel quantity in the exhaust system.
• the non-torque-forming injection can thus be detected even after ignition of the fuel in the engine.
• the application of the drive voltage to the at least one actuator causes no opening of the injection valve, if the determined fuel content is less than the comparison value, and that the application of the drive voltage to the at least one actuator causes an opening of the injection valve, if the determined fuel content is greater than the comparison value.
• the application of the drive voltage to the at least one actuator causes an opening of the injection valve, if the determined fuel content is greater than the comparison value.
• the fuel content in the exhaust gas tract is determined by means of a lambda probe.
• a lambda probe Conventionally, almost all vehicles weighing more than 1,500 kg are equipped with a lambda sensor, which is designed to ensure that the specified emission limits are complied with.
• a lambda probe allows a reliable detection of a made non-torque-forming injection.
• the application of the drive voltage to the at least one actuator is preferably carried out at a piston position in which no torque is released when a fuel possibly injected into the engine is burned. In this way, noise generation during the execution of the method can be almost completely prevented.
• the application of the drive voltage to the at least one actuator is performed at a piston position at which the fuel possibly injected into the engine is no longer ignited. This prevents the performance of the process from causing combustion noise or heat.
• This embodiment of the method is therefore particularly well suited for performing while driving.
• a rail pressure can be measured and the function of the injection valve can be evaluated depending on the rail pressure. The method thus also takes into account the relation between the drive voltage necessary for opening the injection valve and the currently present rail pressure.
• an output value for the drive voltage is specified at the beginning of the method.
• Such an output value can be, for example, the drive voltage specified by the manufacturer for the newly manufactured injection valve at the current rail pressure.
• the drive voltage is increased by a first predetermined voltage difference and the method is repeated at least once more to determine a drive voltage as the newly determined drive voltage, applying this to the at least one actuator Opening the injector causes.
• the method can thus be used not only to determine whether there is a drift on the at least one actuator or on the switching chain of the injection valve.
• a drive voltage suitable for opening the injector can be redetermined.
• the drive voltage can be reduced by a second predetermined voltage difference, the method can be repeated at least once again, and then the smallest drive voltage can be determined as the newly determined drive voltage when it is applied to the at least one actuator an opening of the injection valve is determined.
• the second voltage difference can be chosen to be much lower than the first voltage difference. This makes it possible to determine the smallest drive voltage, which causes an opening of the injection valve, relatively accurately.
• the drive voltage to be applied to the respective actuator can be redetermined depending on the rail pressure.
• the determined correction values can then be stored individually in a correction map.
• a characteristic curve for an optimum drive voltage as a function of the rail pressure is determined.
• a number of empty points are set, which allow a sufficiently clear identification of the actuator.
• the installed actuators are in the presence of the corresponding shares, which are, for example, a rail pressure, an exhaust gas temperature or other stationarities, successively measured the empty points with their An Kunststoffschreibsvariationen. If all empty points of the actuator have been measured, the fingerprint created in this way is compared with the minimum voltage requirement values originally stored for this actuator and stored in the map. These map values are then available for a correction of the charging voltage control of the individual actuators.
• FIG. 1 shows a flowchart of a first embodiment of the method for assessing an operation of an injection valve upon application of a drive voltage
• FIG. 2 shows a flow chart of a second embodiment of the method
• FIG. 3 shows a schematic structure for illustrating a function of the evaluation device for assessing an operation of an injection valve upon application of a drive voltage.
• FIG. 1 shows a flowchart of a first embodiment of the method for assessing an operation of an injection valve when a drive voltage is applied.
• a comparison value RO for a fuel content in an exhaust tract is specified (step SO).
• the comparison value RO is, for example, a fuel quantity or a fuel / air ratio.
• the comparison value RO corresponds to a fuel content in the exhaust gas tract after a non-torque-forming injection of fuel into the associated internal combustion engine.
• the step SO is preferably carried out by the manufacturer before the injection valve is put into operation. The Einspitzventil is then installed in a vehicle.
• a drive voltage U for a non-torque-forming injection is applied to the at least one actuator of the injection valve.
• the at least one actuator is a piezoelectric actuator.
• the application of the drive voltage U takes place, for example, in a piston position in which no torque is released when a fuel possibly injected into the engine is burnt.
• the piston position can be selected so that a possibly injected into the engine fuel is not ignited.
• the drive voltage U is, for example, the drive voltage predetermined by the manufacturer of the injection valve at the currently present rail pressure p.
• the drive voltage U can also be selected with regard to a current exhaust gas temperature.
• a fuel content R (U) in the exhaust gas tract is determined.
• the fuel content R (U) can be, for example, a fuel quantity or a LuIV fuel ratio in the exhaust gas tract.
• the fuel content R (U) is compared with the comparison value RO in step S3. In this way, it should be determined whether, when the drive voltage U is applied to the at least one actuator, the injection valve is opened and a fuel is injected into the internal combustion engine.
• step S4 If the measured fuel content R (U) is smaller than the comparison value RO, it is determined in step S4 that the application of the drive voltage U to the at least one actuator does not cause any opening of the injection valve. If there is no opening of the injection valve when the drive voltage U is applied, this indicates a probable drift of the at least one actuator or the switching chain. In this case, it is necessary to re-determine the control voltage U required for opening the injection valve so that the desired injection quantities are reliably maintained during further operation of the injection valve. A corresponding message is then output.
• step S5 If the measured fuel content R (U) is above the comparison value RO, the application of the drive voltage U to the actuator causes the injection valve to open and thus to be activated Injecting fuel into the internal combustion engine. This is determined in step S5. Also in this case, a corresponding message is issued.
• FIG. 2 shows a flowchart of a second embodiment of the method for assessing an operation of an injection valve when a drive voltage is applied.
• step S0O an output drive voltage U0, a voltage difference ⁇ U and the previously described comparison value RO are specified for a fuel content in the exhaust gas tract.
• this step S10 is carried out by the manufacturer of the injection valve before it is put into operation.
• the output drive voltage UO is, for example, a suitable for opening the new injector drive voltage, which is determined by the manufacturer specifically for this injector.
• the voltage difference .DELTA.U will be discussed in more detail below.
• the method is started in a step SlIa to examine the at least one actuator and the switching chain of the injection valve with regard to a possible drift.
• a current rail pressure p is measured.
• a drive voltage U is selected from the provided output drive voltages UO (step S11).
• the drive voltage U for a non-torque-forming injection is applied to the at least one actuator of the injection valve. It is particularly advantageous if the drive voltage U is applied to the at least one actuator of the injection valve only when the pistons are in a position in which a fuel possibly injected into the engine is no longer ignited. A possible injection of fuel into the engine thus hardly influences the functioning of the engine. Possible noise changes, such as engine noise or combustion noise, are avoided in the injection initiated as a post-injection. Likewise, no torque change is caused, which is why the method is also applicable during normal driving operation.
• a fuel content R (U) for example a fuel quantity or a fuel / air ratio, is determined in the exhaust gas tract.
• the fuel content R (U) is determined by the fuel / air Ratio measured in the exhaust system by means of the lambda probe and then evaluated with the measured value of a mounted inside the air supply air flow meter. Since the air flow meter and the lambda probe are conventionally already installed in many vehicles, this embodiment of step S13 can be carried out without having to install an additional sensor on the vehicle.
• step S14 the determined fuel content R (U) is compared with the comparison value RO. If the fuel content R (U) is smaller than the comparison value RO, then it is determined that no opening of the injection valve occurs when the drive voltage U is applied to the at least one actuator. This indicates a drift of the at least one actuator or the switching chain of the injection valve. It is therefore advantageous if the drive voltage U for opening the injection valve is redetermined in this situation.
• a subsequent method step S15 the drive voltage U is increased by the voltage difference .DELTA.U. Subsequently, the method steps S12 to S14 are carried out again for the newly determined drive voltage U. If, once again, the determined fuel content R (U) is below the comparison value RO, the method steps S15 and S12 to S14 are repeated. This happens until a fuel content R (U) is determined, which is above the comparison value RO.
• a fuel content R (U) above the comparison value RO it is determined that when the drive voltage U is applied to the at least one actuator, the injection valve is opened (but not shown in FIG. 2).
• the smallest drive voltage U at which a fuel content R (U) is determined to be greater than the comparison value RO is then defined as the newly determined drive voltage Un (p).
• a fingerprint for the respective drift of the at least one actuator and / or the switching chain can then be determined.
• a new characteristic curve for a suitable drive voltage U for opening the switching valve as a function of the respective rail pressure p can be determined on the basis of this fingerprint.
• the drive voltage U can be reduced by a predetermined minimum voltage difference.
• the minimum voltage difference is preferably significantly smaller than the voltage difference .DELTA.U.
• the steps S12 to S14 are then carried out until a fuel content R (U) is again measured below the comparison value RO. In this way, the smallest drive voltage U determine at which just a fuel content R (U) above the comparison value RO is determined.
• Such an iteration step may be performed to set an even more accurate drive voltage Un (p).
• the newly determined drive voltage Un (p) can then, as described above, evaluated and / or used to operate the injector. However, it is also possible to dispense with such an iteration step for more accurately determining the newly determined drive voltage Un (p), for example by setting a relatively small voltage difference ⁇ U.
• the fuel content can also be determined as the air / fuel ratio.
• an opening of the injection valve can be determined if the determined air / fuel ratio is smaller than a predetermined comparison value. Failure to open the injection valve despite application of a drive voltage is then detected if the determined air / fuel ratio is greater than a predetermined comparison value. However, this is not shown in FIGS. 1 and 2.
• FIG. 3 shows a schematic structure for illustrating a function of the evaluation device for assessing an operation of an injection valve when a drive voltage is applied to an actuator of the injection valve.
• the injection valve 10 to be examined is arranged between a fuel tank 12 and an internal combustion engine 14. When the injection valve 10 is opened, fuel is injected from the fuel tank 12 into the engine 14.
• the internal combustion engine 14 is also connected to an air supply 16. Within the air supply 16, an air flow meter 18 is arranged, which measures the amount of air filled in the internal combustion engine 14 and provides a corresponding first sensor signal 20.
• the internal combustion engine 14 has an outlet to an exhaust tract 22.
• a lambda sensor 24 is arranged within the exhaust tract 22.
• the lambda sensor 24 is designed to determine a fuel / air ratio in the exhaust gas tract 22 and to provide a corresponding second sensor signal 26.
• an engine sensor system 28 is arranged on the internal combustion engine 14 with which a piston position can be determined.
• a third sensor signal 30 provided by the engine sensor 28 includes the angle after the top dead center and is output to an injection controller 32.
• the injection control unit 32 is configured after receiving the third sensor signal 30 with the angle after the top dead center of the engine sensor 28 to control the injection valve 10 by means of a voltage applied to at least one actuator (not shown) voltage signal 34 so that the injection valve 10 at a certain angle after the top dead center 30 is opened or closed.
• the evaluation device 36 receives a fourth sensor signal 40 via a receiving device 36a with a rail pressure p determined by an onboard pressure sensor 38.
• An output device 36b of the evaluation device 36 then outputs a drive voltage U corresponding to the rail pressure p as a control signal 42 to the injection control device 32.
• the injection control unit 32 is controlled by the control signal 42 such that it applies a voltage signal 34 corresponding to the drive voltage U for a non-torque-forming injection to the actuator of the injection valve 10. For example, the injection control unit 32 waits for an angle after the top dead center, at which a fuel injected into the internal combustion engine 14 is no longer ignited.
• the engine sensor system 28 may also output the third sensor signal 30 with the determined angle after the upper dead center 30 to the evaluation device 36.
• the evaluation device 36 outputs the control signal 42 to the injection control device 32 only at a certain angle after the top dead center.
• the evaluation device 36 receives from the lambda sensor 24 the second sensor signal 26 with the measured fuel / air ratio in the combustion tract 22. In addition, the evaluation device 36 receives from the air flow meter 18 the first sensor signal 20 with the amount of air filled in the internal combustion engine 14. A comparison device 36c of the evaluation device 36 then uses this data to determine the amount of fuel introduced into the internal combustion engine 14. Subsequently, the calculated fuel quantity is compared with a comparison value RO. If the fuel quantity injected into the internal combustion engine 14 is above the comparison value RO, then the evaluation device 36 recognizes that the injection valve 10 is opened when the respective control voltage U is applied to the at least one actuator.
• the evaluation device 36 recognizes that the application of the drive voltage U to the at least one actuator of the injection valve 10 does not cause the injection valve 10 to open.
• the respective drive voltage U is thus unsuitable for opening the injection valve 10. If this drive voltage U corresponds to the value specified by the manufacturer for the new injection valve 10, then there is a drift of the at least one actuator and / or the switching chain.
• the minimum required voltage requirement can be repeated by the evaluation device 36 by repeating the described measuring method with changed drive voltages U.
• the minimum required control voltage U for an injection determined in this manner is subsequently stored in individual characteristic maps in the cylinder and is thus available for drift compensation of the actuators.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
• Fuel-Injection Apparatus (AREA)
• Combined Controls Of Internal Combustion Engines (AREA)

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• 2007
  • 2007-09-10 DE DE102007042994A patent/DE102007042994A1/de not_active Withdrawn
• 2008
  • 2008-07-23 PL PL08786345T patent/PL2201236T3/pl unknown
  • 2008-07-23 CN CN2008801062493A patent/CN101802379B/zh not_active Expired - Fee Related
  • 2008-07-23 WO PCT/EP2008/059653 patent/WO2009033869A1/de active Application Filing
  • 2008-07-23 US US12/600,802 patent/US8700288B2/en not_active Expired - Fee Related
  • 2008-07-23 EP EP08786345A patent/EP2201236B1/de not_active Not-in-force
  • 2008-07-23 JP JP2010524429A patent/JP5140731B2/ja not_active Expired - Fee Related

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